GUIDE North America case study: CO2 / Ammonia brine system for distribution center

shecco’s North American GUIDE features a case study by CIMCO, who designed and installed an ammonia/CO₂ system for Canadawide’s expanding distribution center. Published in the “GUIDE 2013: Natural Refrigerants - Market Growth for North America” the case study looks at the new state-of-the art-refrigeration system, installed at the Montreal warehouse, which has proven to be more energy efficient than the alternative Freon design.

Canadawide, a national wholesaler of fruits and vegetables, in 2011 commissioned CIMCO, Canada's largest industrial refrigeration organisation, to install a new refrigeration system to refrigerate 5,575m². After considering several designs, Canadawide opted for an ammonia/CO₂ brine refrigeration system, finding that it would align best with their objectives.

Patrick Ianniciello, the Project Manager, made the following comments during the start up procedure. “In my entire career I have never seen room temperatures going down so fast, this system is operating like crazy, and I would recommend this system over any other I’ve seen.’’

About the CO₂/ammonia system

The CIMCO-designed system uses medium temperature ammonia as the primary refrigerant to cool a single loop of re-circulated CO₂, which feeds the various evaporators. The CO₂/ ammonia refrigeration system provides cooling for a warehouse that has 8 coolers from -4°C to 5°C (24.8°F to 41°F), 17 loading docks and 8 banana rooms.

The system features the following:

Two 150 kW industrial screw compressors with ammonia evaporation at -11°C (51.8°C) and ammonia condensation at 35°C (95°F)
Low-height centrifugal motor condenser
Internal sump tank and pump used because of harsh winter conditions
High side pressure float to feed the ammonia/CO₂ cascade cooler
CIMCO shell and tube one-pass cascade cooler
Plate and frame ammonia/glycol cooler

Economiser port, modular valve assembly, and modulating solenoid valves installed

To increase efficiency, the screws utilise the economiser port to sub-cool the liquid. Each refrigeration evaporator is also equipped with modular valve assemblies.

To minimise dehydration of higher temperature rooms, since the entire system is fed via one loop of recirculated CO₂ at -6.6°F (20.1°F), special modulating liquid solenoid valves have been installed.

For defrost, the higher temperature 7°C (44.7°C) rooms use ambient air defrost, while the lower temperature rooms are equipped with electric defrost.

About CIMCO

Over the years CIMCO has grown into an international refrigeration leader in the industrial refrigeration food and beverage and cold storage markets. CIMCO’s specialities include the full spectrum of engineering, designing, manufacturing, installing and servicing of industrial, process cooling and recreational refrigeration systems.